This proposal is designed to develop islet transplantation in diabetic animals by protecting isolated islet tissue from rejection through the use of a specific semi-permeable membrane in a transplantation chamber. The use of isolation and tissue culture techniques should supply a fibroblast-free source of graft tissue. The development of precise membranes for this application is designed to exclude antibodies while permitting diffuson of glucose, insulin, and nutrients. The development of regional anti-coagulation for the intravascular model and fibroresistant surfaces for the extravascular model will complete the requirements for long survival at minumim risk. With insulin's inability to prevent the secondary complications of diabetes, it is imperative that alternative forms of treatment be found.